11

Timber-framed
Systems for External Noise
Technical Design Guide issued by Forest and Wood Products Australia


01

04

09

Building with Timber
in Bushfire-prone Areas
BCA Compliant Design and Construction Guide
Technical Design Guide issued by Forest and Wood Products Australia

Timber-framed Construction
for Townhouse Buildings
Class 1a
Design and construction guide for BCA compliant
sound and fire-rated construction

Timbe
r Floo
ring
for inst

Desig
n guide

Technica

l Desi

Technical Design Guide issued by Forest and Wood Products Australia

gn Guid

e issu

ed by

Forest

allatio
n

and Woo

d Prod

ucts

Australia

Technical Design Guides
A growing suite of information, technical and
training resources created to support the use of
wood in the design and construction of buildings.

Topics include:
#01 Timber-framed Construction for
Townhouse Buildings Class 1a
#02 Timber-framed Construction for
Multi-residential Buildings Class 2, 3 & 9c
#03 Timber-framed Construction for
Commercial Buildings Class 5, 6, 9a & 9b
#04 Building with Timber in Bushfire-prone Areas
#05 Timber service life design Design Guide for Durability
#06 Timber-framed Construction Sacrificial Timber Construction Joint
#07 Plywood Box Beam Construction
for Detached Housing
#08 Stairs, Balustrades and Handrails
Class 1 Buildings - Construction
#09 Timber Flooring - Design Guide for Installation
#10 Timber Windows and Doors
#11 Timber-framed Systems for External Noise
#12 Impact and Assessment of
Moisture-affected, Timber-framed Construction
#13 Finishing Timber Externally
#14 Timber in Internal Design
#15 Building with Timber for Thermal Performance
#16 Massive Timber Construction Systems
Cross-laminated Timber (CLT)
Other WoodSolutions Publications
R-Values for Timber-framed Building Elements
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visit woodsolutions.com.au

WoodSolutions is an industry initiative designed to provide

independent, non-proprietary information about timber and
wood products to professionals and companies involved in
building design and construction.
WoodSolutions is resourced by Forest and Wood Products
Australia (FWPA – www.fwpa.com.au). It is a collaborative effort
between FWPA members and levy payers, supported by industry
bodies and technical associations.
This work is supported by funding provided to FWPA by the
Commonwealth Government.
ISBN 978-1-921763-41-0
Prepared by:
Colin MacKenzie
Timber Queensland Limited
www.timberqueensland.com.au
First published: August 2012
Revised: December 2012
© 2012 Forest and Wood Products Australia Limited.
All rights reserved.
These materials are published under the brand WoodSolutions by FWPA.
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Table of Contents
Introduction

4

1 Methods for Reducing Noise into Buildings

5


1.1 Site Planning and Landscaping .................................................................................................... 5
1.2 Site Specific Assessment and Design .......................................................................................... 6
1.3 Building Envelope Noise Attenuation............................................................................................ 6
2 Regulatory Requirements

7

2.1 Local Authority Requirements ...................................................................................................... 8
2.2 State and Territory Requirements ................................................................................................. 8
2.3 National Construction Code Series – Building Code of Australia................................................ 10
3 Lightweight Timber Solutions

11

3.1 Introduction ................................................................................................................................... 11
3.2 Definitions...................................................................................................................................... 11
3.3 Calculation of Acoustical Performance ......................................................................................... 11
3.4 Guidance and Assumptions for Acoustical Performance ............................................................. 12
3.5 Substitutions.................................................................................................................................. 15
3.6 Wall Systems ................................................................................................................................. 16
3.7 Roof Systems ................................................................................................................................ 30
3.8 Floor Systems ............................................................................................................................... 36
4 Gaps, Services and Penetrations Sealing penetrations

42

5 Further information

43


5.1 Opinions and Assessement Report ............................................................................................. 43

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Introduction
This guide has been prepared to assist the building industry with the key issues to be
considered when assessing alternatives related to external noise using lightweight timberframed construction. The information contained in this guide should not be considered as
standalone, and where appropriate relevant expertise should be obtained. The guide does
not cover matters associated with other aspects of building construction or the regulatory
requirements associated with these.
Noise – it’s everywhere. It impacts on our daily lives, in our homes, work places and during
recreational pursuits. Many factors can and will influence the degree of unwanted noise that enters our
homes and our response to this, including:
•
•
•
•

Owner/occupier expectations
Daytime or nighttime
Ambient background noise levels
Activities being undertaken

One of the most significant sources of unwanted external noise comes from transportation activities –
road, rail and aircraft.
In order of priority there are three main strategies for reducing the intrusion of unwanted external noise
into residential properties:

• Distance separation between the noise source and the property
• External physical noise attenuation barriers
• Noise attenuation of the building envelope
Where the first two methods cannot be satisfactorily achieved, many regulatory juristictions are now
imposing limits on the entry of noise into the habitable areas of dwellings by controlling the design and
construction of the building envelope (roofs, walls and floors).
Key Issues
When designing a new or modifying an existing dwelling, all building work must comply with the
Building Code of Australia (BCA) and any actions to reduce the ingress of external noise must be
designed and constructed to be compatible with all other aspects of the BCA that may apply such as
energy efficiency and bushfire construction requirements.
Considerations include:
• Inner cities tend to generate greater levels of external noise than suburban areas with low frequency
noise from sources such as trucks, construction sites and waste collection being more problematic.
• In suburban areas, residences close to main road and rail corridors may suffer from unwanted
noise and residences close to airports or flight paths may also be exposed to noise sources that
need to be addressed.
• The openings in the external building envelope including the number, size, location and selected
materials for windows and doors will have a major impact on the control of noise that can enter a
building. Careful consideration should be paid to these prior to any upgrading of the exterior walls,
floors and the roof-ceiling system.

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1

Methods for Reducing Noise

into Buildings
In order of priority there are three main options for reducing the intrusion of external
noise into residential properties:
• Adequate distance separation between the noise source and the property
(set-backs and separation strips)
• Physical barriers including noise attenuation barriers (fences, walls etc and
appropriate landscaping and vegetation) and
• Building noise attenuation into the building envelope (walls, floors and roofs)
1.1 Site planning and landscaping
Some of the principles for planning and arranging residential dwellings on a site to help manage and
minimise the intrusion of noise from transport sources include:
• using natural features such as contours and slopes in the siting of dwellings to provide shielding
from noise sources
• using material excavated on site to form mounds around the building to provide protection
• physical separation by using as much distance as possible between the noise source, such as a
road, and the residence
• locating non-sensitive buildings and spaces that are noise tolerant such as landscaped areas,
carparks, open space and garages between the noise source and the more sensitive residential
development. On a larger scale, open space, recreation areas or commercial facilities could be
used to separate noise sources from residential areas
• using structures as a barrier to protect or shield the areas behind such as placing garages,
courtyards and similar between the noise source and the dwelling

(Image courtesy of ASK Consulting Engineers)

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1.2 Site specific assessment and design
In many instances, developers and builders report that it is far more beneficial and economical to
engage acoustic consultants to undertake site specific assessment and design where external noise
sources are required to be addressed in residential construction.
This process typically involves the following steps:
• determine the level of existing external noise exposure (either through site measurements
or modelling)
• determine external treatments that can be applied to emiliorate external noise
(if this option is available)
• determine the facade (openings, walls roofs and floors) treatment that is required
• certification upon completion of work
The Association of Australian Acoustical Consultants (AAAC) have published a guide on levels of
acoustic amenity to provide differing levels of building quality. Ratings range from 2 to 6 stars and are
based on field testing by an AAAC consultant to verify that they have been achieved. More information
about AAAC Star Ratings for dwellings, apartments and townhouses is available at www.aaac.org.au

1.3 Building Envelope Noise Attenuation
Walls including openings, roofs and floors in the external building envelope can be designed and
constructed to minimise the intrusion of unwanted external noise.
Many regulatory juristictions are now imposing limits on the entry of noise into the habitable areas of
dwellings by controlling the design and construction of the building envelope (roofs, walls and floors).
The following section considers some of the regulatory requirements and provides solutions in
lightweight timber construction to meet these requirements.

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2


Regulatory Requirements
Across Australia, many levels of Government and their authorities have regulatory or
legislative powers to require control of noise entering buildings, in particular residential
buildings. These requirements tend to be fairly ‘fluid’ with regular changes requiring
designers and specifiers to keep abreast of new initiatives.
Examples of these requirements include, but are not limited to:-

• noise overlays for aircraft
and airport environments

• road noise corridors

• rail noise corridors
Control and application of these requirements may rest with local governments or state authorities
such as Departments of Building and Planning, Transport or Main Roads etc, and in some cases
(aircraft) at the Federal level.
At the time of publication of this Guide, there were no requirements for the control of external noise
entering buildings contained within the BCA, however, these were under consideration by the
Australian Building Codes Board with draft changes proposed.

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2.1 Local Authority Requirements.
In response to community concerns, many local authorities have been requiring building envelope
treatment for residences which are not protected sufficiently by noise barriers. At the same time some
councils have been restricting the heights of noise barriers for reasons of visual amenity, limiting the

level of noise reduction that can be attained. In conjunction with this height restriction, additional
noise insulation requirements have been placed onto residential allotments which are affected by
unreasonable levels of noise. These requirements have been enforced by either planning instruments,
property notes or covenants to the title.
2.2 State and Territory Requirements
A number of states and territories have legislation that requires developers, designers, certifiers and
builders to limit the intrusion of external noise into residential and other types of building occupancy.
Before considering or applying any external noise control options, consult with your relevant state/
territory body to determine the specific requirements that need to be addressed which may vary from
significant requirements to none.
Some typical examples for some States and Territories are listed below.
New South Wales
Road Traffic Noise
The NSW State requirements for road traffic noise for residential development are contained within
the State Environment Planning Policy (Infrastructure) 2007 Clause 102 – Impact of Road Noise or
Vibration on Non-road Development. This clause states that if the development is for the purposes of a
building for residential use, the consent authority must not grant consent to the development unless it
is satisfied that appropriate measures will be taken to ensure that the following energy averaged noise
levels (LAeq) are not exceeded; (a) in any bedroom in the building - 35 dBA at any time between 10
pm and 7 am, (b) anywhere else in the building (other than a garage, kitchen, bathroom or hallway) 40 dBA at any time.
Rail Traffic Noise
The NSW rail noise and vibration requirements are found, for example, in Infrastructure SEPP Clause
87 Impact of Rail Noise or Vibration on Non-Rail Development 2007, NSW. Clause 87 states that if the
development is for the purposes of a building for residential use, the consent authority must not grant
consent to the development unless it is satisfied that appropriate measures will be taken to ensure
that the following energy averaged noise levels (LAeq) are not exceeded; (a) in any bedroom in the
building - 35 dBA at any time between 10 pm and 7 am, (b) anywhere else in the building (other than a
garage, kitchen, bathroom or hallway) - 40 dBA at any time.
Aircraft Traffic Noise
An acoustical report to comply with the Australian Standard AS 2021 – 2000 “Acoustics – Aircraft Noise

Intrusion - Building Siting and Construction” is often required by Council’s Development Consent for
sound insulation against air traffic noise.
Queensland
Traffic Noise
The Queensland Development Code (QDC) MP 4.4 “Buildings in transport noise corridors” provides
for construction standards for minimum traffic noise reduction levels which are to be achieved across
four noise categories. These noise categories provide for a weighted sound reduction index (Rw) which
determines appropriate building materials for the floor, walls, roof, windows and doors. These building
materials are to restrict the amount of external noise entering habitable rooms of a residential building.
Mandatory Part (MP) 4.4 was introduced into the Queensland Development Code (QDC) on 1
September 2010. QDC MP 4.4 is to be used by building certifiers when assessing residential buildings
within a transport noise corridor’.
A Transport Noise Corridor is defined by agencies such as the Department of Transport and Main
Roads (TMR), Queensland Rail and local authorites. At the time of this study, corridors had only been
assigned by TMR for most major roads in Queensland. The Code defines five noise categories based
on the noise exposure level. Category 4 is the highest and Category 0 the lowest.

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The categories are assigned based only on the distance from the road and the characteristics of
the road and do not account for constructed noise barriers and terrain features which may shield
properties.
The Code allows a reduction in the noise category using a noise model to predict the noise exposure
which can account for screening effects from barriers, terrain and other buildings present between the
road and the residence being assessed. This typically results in a reduction in the noise category. For
each of the noise categories the following ratings are required by QDC MP 4.4:
Noise Reduction Performance for Various Building Elements


Category

Building Element Sound Reduction Requirement (Rw)
Glazing
(Area

External
walls

Roof

Floors

Entry Doors

Dependent)

Category 4

43

52

45

51

35


Category 3

35-38

47

41

45

33

Category 2

32-35

41

38

45

33

Category 1

24-27

35


35

NR

28

Category 0

No additional acoustic treatment required – standard building
assessment provisions apply.

Note: NR = Not required

Victoria
In Victoria there are no specific, statewide regulations for noise, however the special noise control
overlay for Melbourne Airport does introduce some requirements, see specific noise control section
below.
Australian Capital Territory
In the ACT, the mechanisms available for management of noise levels include:
• regulation of noise emissions at the source (Noise Control Act 1988 administered by the Pollution
Control Authority);
• planning control over land use and set-back distances, and design of buildings, necessary to
separate noise generating activities from noise sensitive land uses;
• planning and development requirements for provision of noise attenuation measures, including
building design, materials used and construction techniques/practices.
Traffic Noise
A draft Noise Management Guidline has been published by the ACT Planning Authority which sets out
guidelines for desirable and maximum levels of noise from traffic and land use activity, and advises on
methods to prevent or reduce excessive noise levels. The guidelines do not remove the requirement to
comply with the Noise Control Act 1988.

The objectives of the noise management guidelines are to ensure that:
• developments with the potential to introduce new noise sources, whether a road or a land use
activity, are designed to ensure that noise in adjacent areas is kept within acceptable limits; and
• new noise-sensitive developments are protected from unacceptable noise levels generated by
existing sources.

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Western Australia
In most cases transportation noise is not subject to the Environmental Protection (Noise) Regulations
1997 because it is regulated by one of several other means.
Vehicle Noise
Traffic noise from roads is exempt from the Environmental Protection (Noise) Regulations 1997.
Instead, the Road Traffic (Vehicle Standards) Rules 2002 address community concern about noisy
trucks, cars and motorbikes.
Rail Noise
Noise emissions from rail are exempt from the noise regulations.
Aircraft Noise
Whether it is as a result of ground operations or from aircraft whilst in flight, it is covered under federal
legislation and managed by an Aircraft Noise Strategy.
Specific Noise Control
In a number of specific situations, special overlays may apply to certain areas. For instance the The
Melbourne Airport Environs Overlay is a set of planning rules, or controls, designed to help state and
local government plan for the environmental effects of aircraft noise associated with Melbourne Airport.
2.3 National Construction Code Series - Building Code of Australia (BCA)
Currently there is no National code for external noise, however the Australian Building Code Board had
drafted amendments proposed to address external noise intrusion for consideration by the BCA. At

the time of publication of this guide the BCA had requested further consultation and development of
the proposal.

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3

Lightweight Timber Solutions
3.1 Introduction
The Weighted Sound Reduction Index (Rw) and Low-frequency Spectrum Adaptation Term (Rw+ Ctr)
ratings for various systems given in Sections 3.6 to 3.8 have been derived using information from
existing published tests and calculations of performance using the ‘Insul’ computer software. This
information is based on a report provided by acoustic consultants.

3.2 Definitions
Weighted Sound Reduction Index (Rw)
The Weighted Sound Reduction Index (Rw) refers to a single number acoustic rating calculated
from the reduction in noise between two rooms. A higher rating indicates less sound transmission
and higher performance. Rw is assessed over the frequency range 100-3150Hz using the sum of
deviations less than 32 dB method and is calculated using formulae in AS/NZS/ISO 717.1 2004
Acoustics---Rating of sound insulation in buildings and of building elements Part 1: Airborne sound
insulation.
Low-frequency Spectrum Adaptation Term (Rw+ Ctr)
The Rw + Ctr parameter is also calculated using formulae in AS NZS ISO 717.1 2004
The Ctr term refers to a correction factor that adjusts the Rw to take into account low frequency noise. If
the noise being transmitted contains a large element of low-frequency noise, then the correction factor
will lower the Rw rating to reflect this low-frequency noise intrusion. For nearly all building elements,

low frequency transmission is poorer than for speech therefore the Ctr term is usually negative.
STC
STC or Sound Transmission Class is a single number rating for partitions. It is calculated or derived
from 1/3 octave band Sound Transmission Loss data by a method described in American Society for
Testing Materials standard ASTM E316. The frequency range for assessment of STC is 125-4000 Hz.
It also uses the sum of deviations less than 32 dB method and includes a limitation of no octave more
than 8 dB below the rating curve.
In general the two ratings (STC and Rw) give either the same number or are only 1-2 points difference,
so they can be used fairly interchangeably.
3.3 Calculation of Acoustical Performance
Levels of acoustic performance have been calculated using the industry standard ‘Insul’ software.
( Allowances have been made for mass of various materials and “ideal”
workmanship. Publishers of the ‘Insul’ software claim that comparisons with “calculated performance”
with test data show that it is generally within 3 STC/Rw points for most constructions.

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Factors taken into account in calculation of acoustical performance include the surface mass of the
material, Young’s Modulus, edge damping, the critical frequency and speed of sound in materials,
the effect of air cavities and acoustic insulation between members. The Rw values determined and
provided in this guide are laboratory values. These estimations of performance can be used for
requirements of performance stated in building or planning regulations and other calculation methods,
such as AS3671, which also refer to laboratory values.
3.4 Guidance and assumptions for acoustical performance
The performance estimates are based on laboratory quality construction with a high attention to detail.
Calculated levels of performance are based on:
• external wall elements being sealed to near-to-air-tight construction which is fully caulked and

sealed
• internal plasterboard layers are constructed, caulked, sealed and using details as recommended
by the plasterboard manufacturer
Opinions of performance may not be valid where installation details such as stud spacing and fixing
centres do not match those used in the nominated systems.
The systems are specifically derived for external noise intrusion and no consideration is given to
internal wall construction noise ratings i.e noise travelling between internal rooms. No references are
made for the rating of impact noise as impact noise is not an issue for external noise intrusion.
The issue of flanking noise is not considered as estimates are laboratory based and flanking is
purposely controlled. For application in the field, flanking should be carefully considered to ensure
performance is delivered. If the selection of the acoustical performance of building elements are being
made to deliver a result in the field which is not in accordance with a requirement which requires
laboratory acoustical performance, an acoustic consultant should be consulted to provide detailed
recommendations for construction.
Timber Types
Acoustical opinions were provided for the following wall constructions:
• 70mm studs are 35 or 45 mm thickness
• 90mm studs are 35 or 45 mm thickness
• may consist of softwood, hardwood or engineered timber product
• in standard walls, noggins may be full depth of stud or alternatively lesser depth as per AS 1684
• for the use of staggered studs, where noggings are installed, noggings on the outer studs must not
touch the inner studs and vice versa. This may necessitate the use of thin noggings on edge.
A typical staggered stud arrangement without noggings is shown in Figure 1
• For pitched roof/ceiling systems, cathedral ceilings and floor construction all timber product types
are acceptable including solid timber and engineered timber products such as ‘I’ joists, LVL,
Glulam and trusses.

INSULATION

STAGGERED

STUD

BOTTOM PLATE

Figure 1: Plan view of Staggered stud wall system

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Insulation
(a) Glasswool (GW)
Insulation nominated in this guide is glasswool. Glasswool insulation has been used as there is an
Australian Standard for glasswool manufacture and the product remains consistent.
Any glasswool insulation of greater thickness and density to that nominated can be substituted to
achieve better acoustic insulation. This additional insulation will improve performance to a value
greater than the estimates. In most cases the addition of further insulation either by thickness or
density will slightly improve the performance of a system, particularly at low frequency; however the
overall improvement may only be 1 dB.
Insulation used should not be thicker than the cavity size as bridging can occur.
Should an upgrade in acoustical performance above and beyond the values provided in this manual
be required with the addition of insulation, advice from an acoustic engineer should be sought.
(b) Polyester Insulation
The substitution of polyester insulation is acceptable for the nominated systems on the basis that
equivalent or better thickness and density is provided.
Care should be taken when using polyester insulation as there is currently no Australian Standard for
its manufacture. Should there be any concern over quality of product used in substitution advice from
an acoustic engineer should be sought.
Plasterboard

Where plasterboard is referred to in this manual it is plasterboard constructed in accordance with:
AS/NZS 2588:1998 Gypsum Plasterboard.
Minimum permissible masses are as follows:
• 10mm plasterboard (Pbd): 6.5kg/m2
• 13mm plasterboard (Pbd): 8.5kg/m2
• 16mm fire-rated plasterboard (FR Pbd): 12.5kg/m2
Ventilated Eaves
A common feature of timber framed building is the use of ventilated eaves which are connected to the
roof cavity. Ventilated eaves result in acoustical weakness unless treated correctly.
It is acknowledged that the use of ventilated eaves are necessary in specific situations. In areas where
buildings require acoustical ratings of external elements, detailing is required to preserve acoustical
integrity of the building through this path. One method of addressing this is to provide glasswool
packed tightly over top plates of walls under the roof sheeting/tiles.
In situations where consideration is given to orientation of the building to a noise source, ventilation
of a roof space can be achieved by orientation of the ventilation slots/holes on the leeward side of the
building.
Resilient Steel Wall Channels
Where nominated in the details and ratings in Section 3.6, resilient steel wall channels may be fixed
vertically to studs or horizontally across studs in accordance with manufacturers requirements.
The channels may also be located on either the inside of the wall or the outside of the wall without
affecting the acoustic ratings given.
Where located on the external side of the wall to support cladding, particular attention should be paid
to manufacturers recommendations regarding installation to resist relevant wind pressures.
Figure 2 illustrates a typical proprietary side fixed resilient wall channel used to support the internal
lining.

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EXTERNAL
CLADDING

TYPICAL PROPRIETARY
RESILIENT WALL CHANNEL
FIXED TO WALL STUDS

WALL STUD

NOGGING

INTERNAL LINING

INSULATION

Figure 2: Resilient mounted wall cladding. Vertical section through wall

Resilient Mounted Ceilings
Where ceilings are required to be resiliently mounted, the typical detail given in Figure 3 may be used.

FIXING

RESILIENT MOUNT
WALL ANGLE
FURRING CHANNEL
ACOUSTIC FOAM STRIP
CEILING LINING

Section Through Corner Fixing Angle


CEILING LINING

Ceiling Furring Channel

Figure 3: Resilient mounted ceiling lining. Resilient mount and furring channel detail

Floor Zones
Ratings are nominated in this guide for elevated floors which are open to the exterior via an opening.
Perimeter sub-floors covered with open mesh, slats or perforated material which allow the air to freely
pass do not provide a noise reduction and the ratings in the table should be used without adjustment.
In situations where the underfloor area is built-in around the perimeter of the building with the minimum
BCA ventilation opening requirements, an improvement to the noise transmission path through the
floor is provided. With the opening requirement of 7500mm2/m of wall length not being exceeded,
using continuous brick, block, or, fibre cement linings, an estimated improvement to the Rw and
Rw+Ctr rating of the floors is 15 dB. For continuous 0.42mm BMT metal sheeting which is connected
to solid elements at the periphery an improvement of 10 dB is expected with the minimum opening
requirement.

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3.5 Substitutions
In using the nominated opinions in this guide, it is possible that a slightly different system may be
sought. If changes to a system are made, the changes will modify the acoustical performance in the
following ways:
Cavity, insulation and sarking changes
• Increasing the thickness and density of the insulation will improve the performance slightly.

Polyester insulation of equivalent or greater thickness and density may be substituted for the Glass
Wool (GW) insulation.
• Increasing the cavity between the inner and outer layer will improve the performance.
• Omission of wall or roof sarking will not effect the acoustic ratings
• When a batten is used on the outer layer of the system, sheeting elements can be grouped
together or separated using the batten without affecting the performance.
Stud Changes
• Increasing the thickness of studs and battens will decrease the performance and should be
avoided.
• For systems using 70mm studs and batten a 90mm stud without batten may substituted without
changing the performance.
• For wall systems other than Brick veneer and staggered studs, the reduction of stud spacing from
600mm centres to 450mm centres reduces the Rw and Rw+Ctr performance by 1 dB due to the
additional connections.
• For brick veneer and staggered studs wall systems, there is no reduction in Rw and Rw+Ctr
performance changing the stud spacing from 600mm to 450mm.
• Bridging staggered studs with noggings will negate the performance improvements back to that of
a normal stud wall
Sheeting and lining Changes
• Medium Density Fibreboard (MDF) of equivalent density to plasterboard can be substituted for
plasterboard and the same degree of performance obtained if the same arrangements of caulking
and sealing are applied as per the plasterboard.
• Fibre cement sheeting (6mm thickness) provides slightly better acoustical performance than
standard-core plasterboard and can therefore be substituted for 10 or 13mm plasterboard in any of
the systems using 10 or 13 mm plasterboard and the same performance achieved.
• One layer of 10mm plasterboard plus one layer of 16 mm plasterboard may be substituted for two
layers of 13 mm plasterboard.
• Hardboard (6.4mm) thickness provides equivalent acoustical performance to standard-core
plasterboard and can therefore be substituted for 10mm plasterboard in any of the systems using
10mm plasterboard.

For any other substitutions, or for the application of any other special proprietary systems or cladding,
advice from an acoustic engineer should be sought.

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3.6 Wall Systems
3.6.1 Timber External Cladding
(i) Weatherboards (Board lap joints to be caulked)

TIMBER
WEATHERBOARD
CLADDING

INTERNAL LINING

TIMBER WALL BATTENS
OR RESILIENT STEEL
CHANNELS (SEE TABLE)

NOGGING

WALL STUD
WALL SARKING
TO STUD FRAMING
WHERE REQUIRED

INSULATION


Figure 4: Weatherboard cladding. Vertical section through wall
External
Cladding

Weatherboard
(25 mm
nominal
thickness).
Board laps
caulked with
a durable
flexible
sealant.

Batten

Frame

Stud Centres
(max)

Internal
Lining

Insulation

Rw

Rw+ Ctr


25

70

600mm

1 x 10mm Pbd

75mm 11 kg/m3 GW

39

34

25

90

600mm

25

120

300mm
staggered

1 x 10mm Pbd


75mm 11 kg/m GW

39

34

1 x 10mm Pbd

75mm 11 kg/m3 GW

44

38

25

70

600mm

2 x 10mm Pbd

75mm 11 kg/m3 GW

41

37

25


90

600mm

2 x 10mm Pbd

75mm 11 kg/m GW

41

37

25

120

300mm
staggered

2 x 10mm Pad

75mm 11 kg/m GW

47

42

25

70


600mm

1 x 13mm Pad

75mm 11 kg/m3 GW

38

34

25

90

600mm

1 x 13mm Pad

75mm 11 kg/m3 GW

39

35

25

120

300mm

staggered

1 x 13mm Pad

75mm 11 kg/m GW

45

39

25

70

600mm

2 x 13mm Pad

75mm 11 kg/m3 GW

41

38

25

90

600mm


2 x 13mm Pad

75mm 11 kg/m GW

41

38

25

120

300mm
staggered

2 x 13mm Pad

75mm 11 kg/m3 GW

48

43

25

70

600mm

1 x 16mm FR

Pad

75mm 11 kg/m3 GW

39

35

25

90

600mm

1 x 16mm FR
Pad

75mm 11 kg/m3 GW

39

36

25

120

300mm
staggered


1 x 16mm FR
Pad

75mm 11 kg/m3 GW

45

41

Resilient
Steel
Channel

90

600mm

2 x 16mm FR
Pad

75mm 11 kg/m3 GW

50

44

3

3
3


3

3

Table 1: Rw and Rw+ Ctr Ratings Weatherboard Clad Walls
NOTES
1. A 90 mm stud without batten may be used in lieu of and at the same rating as a 70 mm stud with a 25 mm batten.
2. For staggered stud wall frames with 120 mm plates, either 70 or 90 mm studs may be used. See also Section 3.4.

#11 • Timber-framed Systems for External Noise

Page 16


(ii) Chamfer Boards or Shiplap Boards (Hardwood or Softwood) of 19 mm thickness

Figure 5: Chamfer Board or Shiplap Board cladding. Vertical section through wall

External
Cladding

Chamfer
Board or
Shiplap
Boards
(19 mm
thickness)

Batten


Frame

Stud Centres
(max)

Internal
Lining

Insulation

Rw

Rw+ Ctr

25

70

600mm

1 x 10mm Pbd

75mm 11 kg/m3 GW

38

33

25


90

600mm

1 x 10mm Pbd

75mm 11 kg/m GW

38

33

25

120

300mm
staggered

1 x 10mm Pbd

75mm 11 kg/m GW

44

38

25


70

600mm

2 x 10mm Pbd

75mm 11 kg/m3 GW

41

37

25

90

600mm

2 x 10mm Pbd

75mm 11 kg/m3 GW

41

37

25

120


300mm
staggered

2 x 10mm Pbd

75mm 11 kg/m GW

47

42

25

70

600mm

1 x 13mm Pbd

75mm 11 kg/m3 GW

38

33

25

90

600mm


1 x 13mm Pbd

75mm 11 kg/m GW

39

34

25

120

300mm
staggered

1 x 13mm Pbd

75mm 11 kg/m3 GW

44

39

25

70

600mm


2 x 13mm Pbd

75mm 11 kg/m3 GW

41

38

25

90

600mm

2 x 13mm Pbd

75mm 11 kg/m GW

41

38

25

120

300mm
staggered

2 x 13mm Pbd


75mm 11 kg/m GW

48

43

25

70

600mm

1 x 16mm FR
Pbd

75mm 11 kg/m3 GW

39

35

25

90

600mm

1 x 16mm FR
Pbd


75mm 11 kg/m3 GW

39

36

25

120

300mm
staggered

1 x 16mm FR
Pbd

75mm 11 kg/m3 GW

45

40

Resilient
Steel
Channel

90

600mm


2 x 16mm FR
Pbd

75mm 11 kg/m3 GW

50

44

3
3

3

3

3
3

Table 2: Rw and Rw+ Ctr Ratings Chamfer Board or Shiplap Clad Walls
NOTES
1. A 90 mm stud without batten may be used in lieu of and at the same rating as a 70 mm stud with a 25 mm batten.
2. For staggered stud wall frames with 120 mm plates, either 70 or 90 mm studs may be used. See also Section 3.4.

#11 • Timber-framed Systems for External Noise

Page 17



(iii) Chamfer Boards or Shiplap Boards (Hardwood or Softwood) of 19 mm thickness
over 6 mm Fibre Cement

Figure 6: Chamfer Board or Shiplap Board cladding over Fibre Cement.
Vertical section through wall

External
Cladding

Chamfer
Board or
Shiplap
Boards
(19 mm
thickness)
with 6 mm
Fibre
Cement
behind

Batten

Frame

Stud Centres
(max)

Internal
Lining


Insulation

Rw

Rw+ Ctr

25

70

600mm

1 x 10mm Pbd

75mm 11 kg/m3 GW

44

38

25

90

600mm

25

120


300mm
staggered

1 x 10mm Pbd

75mm 11 kg/m GW

44

39

1 x 10mm Pbd

75mm 11 kg/m3 GW

49

43

25

70

600mm

2 x 10mm Pbd

75mm 11 kg/m3 GW

46


42

25

90

600mm

2 x 10mm Pbd

75mm 11 kg/m GW

46

42

25

120

300mm
staggered

2 x 10mm Pbd

75mm 11 kg/m GW

52


47

25

70

600mm

1 x 13mm Pbd

75mm 11 kg/m3 GW

43

39

25

90

600mm

1 x 13mm Pbd

75mm 11 kg/m3 GW

43

40


25

120

300mm
staggered

1 x 13mm Pbd

75mm 11 kg/m GW

49

44

25

70

600mm

2 x 13mm Pbd

75mm 11 kg/m3 GW

46

42

25


90

600mm

2 x 13mm Pbd

75mm 11 kg/m GW

46

43

25

120

300mm
staggered

2 x 13mm Pbd

75mm 11 kg/m3 GW

52

48

25


70

600mm

1 x 16mm FR
Pbd

75mm 11 kg/m3 GW

43

40

25

90

600mm

1 x 16mm FR
Pbd

75mm 11 kg/m3 GW

43

40

25


120

300mm
staggered

1 x 16mm FR
Pbd

75mm 11 kg/m3 GW

49

45

Resilient
Steel
Channel

90

600mm

2 x 16mm FR
Pbd

75mm 11 kg/m3 GW

54

48


3

3
3

3

3

Table 3: Rw and Rw+ Ctr Ratings Chamfer or Shiplap Board over 6 mm Fibre Cement clad walls
NOTES
1. A 90 mm stud without batten may be used in lieu of and at the same rating as a 70 mm stud with a 25 mm batten.
2. For staggered stud wall frames with 120 mm plates, either 70 or 90 mm studs may be used. See also Section 3.4.
3. The 6 mm fibre cement board may be located on either the inside or the outside of the batten

#11 • Timber-framed Systems for External Noise

Page 18


(iv) 12 mm Plywood

Figure 7: 12 mm Plywood cladding over Fibre Cement. Vertical section through wall

External
Cladding

12 mm
Plywood


Batten

Frame

Stud Centres
(max)

Internal
Lining

Insulation

Rw

Rw+ Ctr

25

70

600mm

1 x 10mm Pbd

75mm 11 kg/m3 GW

37

31


25

90

600mm

25

120

300mm
staggered

1 x 10mm Pbd

75mm 11 kg/m GW

38

33

1 x 10mm Pbd

75mm 11 kg/m3 GW

42

35


25

70

600mm

2 x 10mm Pbd

75mm 11 kg/m3 GW

41

35

25

90

600mm

2 x 10mm Pbd

75mm 11 kg/m GW

42

37

25


120

300mm
staggered

2 x 10mm Pbd

75mm 11 kg/m GW

47

41

25

70

600mm

1 x 13mm Pbd

75mm 11 kg/m3 GW

38

33

25

90


600mm

1 x 13mm Pbd

75mm 11 kg/m3 GW

38

33

25

120

300mm
staggered

1 x 13mm Pbd

75mm 11 kg/m GW

43

37

25

70


600mm

2 x 13mm Pbd

75mm 11 kg/m3 GW

42

37

25

90

600mm

2 x 13mm Pbd

75mm 11 kg/m GW

42

38

25

120

300mm
staggered


2 x 13mm Pbd

75mm 11 kg/m3 GW

48

42

25

70

600mm

1 x 16mm FR
Pbd

75mm 11 kg/m3 GW

39

34

25

90

600mm


1 x 16mm FR
Pbd

75mm 11 kg/m3 GW

39

35

25

120

300mm
staggered

1 x 16mm FR
Pbd

75mm 11 kg/m3 GW

45

40

Resilient
Steel
Channel

90


600mm

2 x 16mm FR
Pbd

75mm 11 kg/m3 GW

50

42

3

3
3

3

3

Table 4: Rw and Rw+ Ctr Ratings 12 mm Plywood cladding
NOTES
1. A 90 mm stud without batten may be used in lieu of and at the same rating as a 70 mm stud with a 25 mm batten.
2. For staggered stud wall frames with 120 mm plates, either 70 or 90 mm studs may be used. See also Section 3.4.

#11 • Timber-framed Systems for External Noise

Page 19



(v) 9.5 mm Hardboard Planks

Figure 8: 9.5 mm Hardwood Plank cladding. Vertical section through wall

External
Cladding

9.5 mm
Hardboard

Batten

Frame

Stud Centres
(max)

Internal
Lining

Insulation

Rw

Rw+ Ctr

25

70


600mm

1 x 10mm Pbd

75mm 11 kg/m3 GW

43

35

25

90

600mm

25

120

300mm
staggered

1 x 10mm Pbd

75mm 11 kg/m GW

43


35

1 x 10mm Pbd

75mm 11 kg/m3 GW

47

38

25

70

600mm

2 x 10mm Pbd

75mm 11 kg/m3 GW

47

39

25

90

600mm


2 x 10mm Pbd

75mm 11 kg/m GW

47

41

25

120

300mm
staggered

2 x 10mm Pbd

75mm 11 kg/m GW

52

43

25

70

600mm

1 x 13mm Pbd


75mm 11 kg/m3 GW

44

35

25

90

600mm

1 x 13mm Pbd

75mm 11 kg/m3 GW

44

37

25

120

300mm
staggered

1 x 13mm Pbd


75mm 11 kg/m GW

49

40

25

70

600mm

2 x 13mm Pbd

75mm 11 kg/m3 GW

48

41

25

90

600mm

2 x 13mm Pbd

75mm 11 kg/m GW


48

42

25

120

300mm
staggered

2 x 13mm Pbd

75mm 11 kg/m3 GW

53

45

25

70

600mm

1 x 16mm FR
Pbd

75mm 11 kg/m3 GW


45

38

25

90

600mm

1 x 16mm FR
Pbd

75mm 11 kg/m3 GW

45

40

25

120

300mm
staggered

1 x 16mm FR
Pbd

75mm 11 kg/m3 GW


50

43

Resilient
Steel
Channel

90

600mm

2 x 16mm FR
Pbd

75mm 11 kg/m3 GW

55

45

3

3
3

3

3


Table 5: Rw and Rw+ Ctr Ratings 9.5 mm Hardboard Plank cladding
NOTES
1. A 90 mm stud without batten may be used in lieu of and at the same rating as a 70 mm stud with a 25 mm batten.
2. For staggered stud wall frames with 120 mm plates, either 70 or 90 mm studs may be used. See also Section 3.4.

#11 • Timber-framed Systems for External Noise

Page 20


3.6.2 Fibre Cement External Cladding
(i) 7.5 mm Fibre Cement Board (11 kg/m2)

Figure 9: 7.5 mm Fibre Cement Board (11 kg/m2) cladding. Vertical section through wall

External
Cladding

7.5 mm Fibre
cement
(12.2 kg/m2)
(with acrylic
coating

Batten

Frame

Stud Centres

(max)

Internal
Lining

Insulation

Rw

Rw+ Ctr

25

70

600mm

1 x 10mm Pbd

75mm 11 kg/m3 GW

44

37

25

90

600mm


1 x 10mm Pbd

75mm 11 kg/m3 GW

44

37

25

120

300mm
staggered

1 x 10mm Pbd

75mm 11 kg/m GW

48

40

25

70

600mm


2 x 10mm Pbd

75mm 11 kg/m3 GW

47

41

25

90

600mm

2 x 10mm Pbd

75mm 11 kg/m GW

47

41

25

120

300mm
staggered

2 x 10mm Pbd


75mm 11 kg/m3 GW

52

45

25

70

600mm

1 x 13mm Pbd

75mm 11 kg/m3 GW

44

37

25

90

600mm

1 x 13mm Pbd

75mm 11 kg/m3 GW


44

38

25

120

300mm
staggered

1 x 13mm Pbd

75mm 11 kg/m GW

49

42

25

70

600mm

2 x 13mm Pbd

75mm 11 kg/m3 GW


48

42

25

90

600mm

2 x 13mm Pbd

75mm 11 kg/m3 GW

48

43

25

120

300mm
staggered

2 x 13mm Pbd

75mm 11 kg/m GW

53


47

25

70

600mm

1 x 16mm FR
Pbd

75mm 11 kg/m3 GW

44

39

25

90

600mm

1 x 16mm FR
Pbd

75mm 11 kg/m3 GW

44


40

25

120

300mm
staggered

1 x 16mm FR
Pbd

75mm 11 kg/m3 GW

50

44

Resilient
Steel
Channel

90

600mm

2 x 16mm FR
Pbd


75mm 11 kg/m3 GW

54

45

3

3

3

3

Table 6: Rw and Rw+ Ctr Ratings 7.5 mm Fibre Cement External Cladding
NOTES
1. A 90 mm stud without batten may be used in lieu of and at the same rating as a 70 mm stud with a 25 mm batten.
2. For staggered stud wall frames with 120 mm plates, either 70 or 90 mm studs may be used. See also Section 3.4.

#11 • Timber-framed Systems for External Noise

Page 21


(ii) 7.5 mm Fibre Cement Board over 6mm Fibre Cement (20 kg/m2)

Figure 10: 7.5 mm Fibre Cement Board over 6 mm Fibre Cement cladding.
Vertical section through wall

External

Cladding

7.5 mm Fibre
Cement with
6mm Fibre
Cement
behind
(21.2 kg/m2)
(with acrylic
coating)

Batten

Frame

Stud Centres
(max)

Internal
Lining

Insulation

Rw

Rw+ Ctr

25

70


600mm

1 x 10mm Pbd

75mm 11 kg/m3 GW

47

40

25

90

600mm

1 x 10mm Pbd

75mm 11 kg/m3 GW

47

41

25

120

300mm

staggered

1 x 10mm Pbd

75mm 11 kg/m3 GW

52

44

25

70

600mm

2 x 10mm Pbd

75mm 11 kg/m3 GW

50

44

25

90

600mm


2 x 10mm Pbd

75mm 11 kg/m3 GW

50

45

25

120

300mm
staggered

2 x 10mm Pbd

75mm 11 kg/m3 GW

56

49

25

70

600mm

1 x 13mm Pbd


75mm 11 kg/m3 GW

47

41

25

90

600mm

1 x 13mm Pbd

75mm 11 kg/m3 GW

47

42

25

120

300mm
staggered

1 x 13mm Pbd


75mm 11 kg/m3 GW

53

46

25

70

600mm

2 x 13mm Pbd

75mm 11 kg/m3 GW

50

45

25

90

600mm

2 x 13mm Pbd

75mm 11 kg/m3 GW


50

46

25

120

300mm
staggered

2 x 13mm Pbd

75mm 11 kg/m3 GW

56

50

25

70

600mm

1 x 16mm FR
Pbd

75mm 11 kg/m3 GW


47

42

25

90

600mm

1 x 16mm FR
Pbd

75mm 11 kg/m3 GW

47

43

25

120

300mm
staggered

1 x 16mm FR
Pbd

75mm 11 kg/m3 GW


53

48

Resilient
Steel
Channel

90

600mm

2 x 16mm FR
Pbd

75mm 11 kg/m3 GW

57

49

Table 7: Rw and Rw+ Ctr Ratings 7.5 mm Fibre Cement Board over 6 mm Fibre Cement cladding.
NOTES
1. A 90mm stud without batten may be used in lieu of and at the same rating as a 70 mm stud with a 25 mm batten.
2. For staggered stud wall frames with 120 mm plates, either 70 or 90 mm studs may be used. See also Section 3.4.
3. The 6 mm fibre cement board may be located on either the inside or the outside of the batten.

#11 • Timber-framed Systems for External Noise


Page 22


(iii) 9 mm Fibre Cement Cladding

Figure 11: 9 mm Fibre Cement Cladding. Vertical section through wall

External
Cladding

9 mm Fibre
Cement
Cladding
(12.2 kg/m2)

Batten

Frame

Stud Centres
(max)

Internal
Lining

Insulation

Rw

Rw+ Ctr


25

70

600mm

1 x 10mm Pbd

75mm 11 kg/m3 GW

47

40

25

90

600mm

1 x 10mm Pbd

75mm 11 kg/m3 GW

47

41

25


120

300mm
staggered

1 x 10mm Pbd

75mm 11 kg/m3 GW

52

44

25

70

600mm

2 x 10mm Pbd

75mm 11 kg/m3 GW

50

44

25


90

600mm

2 x 10mm Pbd

75mm 11 kg/m3 GW

50

45

25

120

300mm
staggered

2 x 10mm Pbd

75mm 11 kg/m3 GW

56

49

25

70


600mm

1 x 13mm Pbd

75mm 11 kg/m3 GW

47

41

25

90

600mm

1 x 13mm Pbd

75mm 11 kg/m3 GW

47

42

25

120

300mm

staggered

1 x 13mm Pbd

75mm 11 kg/m3 GW

53

46

25

70

600mm

2 x 13mm Pbd

75mm 11 kg/m3 GW

50

45

25

90

600mm


2 x 13mm Pbd

75mm 11 kg/m3 GW

50

46

25

120

300mm
staggered

2 x 13mm Pbd

75mm 11 kg/m3 GW

56

50

25

70

600mm

1 x 16mm FR

Pbd

75mm 11 kg/m3 GW

47

42

25

90

600mm

1 x 16mm FR
Pbd

75mm 11 kg/m3 GW

47

43

25

120

300mm
staggered


1 x 16mm FR
Pbd

75mm 11 kg/m3 GW

53

48

Resilient
Steel
Channel

90

600mm

2 x 16mm FR
Pbd

75mm 11 kg/m3 GW

57

49

Table 8: Rw and Rw+ Ctr Ratings 9 mm Fibre Cement Cladding
NOTES
1. A 90 mm stud without batten may be used in lieu of and at the same rating as a 70 mm stud with a 25 mm batten.
2. For staggered stud wall frames with 120 mm plates, either 70 or 90 mm studs may be used. See also Section 3.4.


#11 • Timber-framed Systems for External Noise

Page 23


(iv) 11 mm Fibre Cement Weatherboards

Figure 12: 11 mm Fibre Cement Cladding. Vertical section through wall

External
Cladding

11 mm Fibre
Cement
Weatherboards
(17.3 kg/m2)

Batten

Frame

Stud Centres
(max)

Internal
Lining

Insulation


Rw

Rw+ Ctr

25

70

600mm

1 x 10mm Pbd

75mm 11 kg/m3 GW

43

35

25

90

600mm

25

120

300mm
staggered


1 x 10mm Pbd

75mm 11 kg/m GW

43

35

1 x 10mm Pbd

75mm 11 kg/m3 GW

47

39

25

70

600mm

2 x 10mm Pbd

75mm 11 kg/m3 GW

46

39


25

90

600mm

2 x 10mm Pbd

75mm 11 kg/m GW

47

41

25

120

300mm
staggered

2 x 10mm Pbd

75mm 11 kg/m GW

52

44


25

70

600mm

1 x 13mm Pbd

75mm 11 kg/m3 GW

43

35

25

90

600mm

1 x 13mm Pbd

75mm 11 kg/m3 GW

43

37

25


120

300mm
staggered

1 x 13mm Pbd

75mm 11 kg/m GW

48

40

25

70

600mm

2 x 13mm Pbd

75mm 11 kg/m3 GW

47

41

25

90


600mm

2 x 13mm Pbd

75mm 11 kg/m GW

48

42

25

120

300mm
staggered

2 x 13mm Pbd

75mm 11 kg/m3 GW

53

46

25

70


600mm

1 x 16mm FR
Pbd

75mm 11 kg/m3 GW

44

38

25

90

600mm

1 x 16mm FR
Pbd

75mm 11 kg/m3 GW

44

39

25

120


300mm
staggered

1 x 16mm FR
Pbd

75mm 11 kg/m3 GW

49

43

Resilient
Steel
Channel

90

600mm

2 x 16mm FR
Pbd

75mm 11 kg/m3 GW

55

48

3


3
3

3

3

Table 9: Rw and Rw+ Ctr Ratings 11 mm Fibre Cement Cladding
NOTES
1. A 90 mm stud without batten may be used in lieu of and at the same rating as a 70 mm stud with a 25 mm batten.
2. For staggered stud wall frames with 120 mm plates, either 70 or 90 mm studs may be used. See also Section 3.4.

#11 • Timber-framed Systems for External Noise

Page 24


(v) 11 mm Fibre Cement Weatherboards over 6 mm Fibre Cement

Figure 13: 11 mm Fibre Cement over 6 mm Fibre Cement Cladding.
Vertical section through wall

External
Cladding

11 mm Fibre
Cement
Weatherboards
with 6 mm Fibre

Cement behind
(17.3 kg/m2)

Batten

Frame

Stud Centres
(max)

Internal
Lining

Insulation

Rw

Rw+ Ctr

25

70

600 mm

1 x 10 mm Pbd

75 mm 11 kg/m3 GW

47


39

25

90

600 mm

25

120

300 mm
staggered

1 x 10 mm Pbd

75 mm 11 kg/m GW

47

41

1 x 10 mm Pbd

75 mm 11 kg/m3 GW

52


44

25

70

600 mm

2 x 10 mm Pbd

75 mm 11 kg/m3 GW

50

44

25

90

600 mm

2 x 10 mm Pbd

75 mm 11 kg/m GW

50

45


25

120

300 mm
staggered

2 x 10 mm Pbd

75 mm 11 kg/m GW

56

49

25

70

600 mm

1 x 13 mm Pbd

75 mm 11 kg/m3 GW

47

41

25


90

600 mm

1 x 13 mm Pbd

75 mm 11 kg/m3 GW

47

42

25

120

300 mm
staggered

1 x 13 mm Pbd

75 mm 11 kg/m GW

53

45

25


70

600 mm

2 x 13 mm Pbd

75 mm 11 kg/m3 GW

50

45

25

90

600 mm

2 x 13 mm Pbd

75 mm 11 kg/m GW

50

46

25

120


300 mm
staggered

2 x 13 mm Pbd

75 mm 11 kg/m3 GW

56

50

25

70

600 mm

1 x 16 mm FR
Pbd

75 mm 11 kg/m3 GW

47

42

25

90


600 mm

1 x 16 mm FR
Pbd

75 mm 11 kg/m3 GW

47

43

25

120

300 mm
staggered

1 x 16 mm FR
Pbd

75 mm 11 kg/m3 GW

53

47

Resilient
Steel
Channel


90

600mm

2 x 16 mm FR
Pbd

75 mm 11 kg/m3 GW

57

51

3

3
3

3

3

Table 10: Rw and Rw+ Ctr Ratings 11 mm Fibre Cement Cladding over 6 mm Fibre Cement
NOTES
1. A 90 mm stud without batten may be used in lieu of and at the same rating as a 70 mm stud with a 25 mm batten.
2. For staggered stud wall frames with 120 mm plates, either 70 or 90 mm studs may be used. See also Section 3.4.
3. The 6 mm fibre cement board may be located on either the inside or the outside of the batten.
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#11 • Timber-framed Systems for External Noise

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